An Introduction to Waveguide Dehydrators

Firehills radar station

The waveguide dehydrator is an important element of any communications waveguide system, be it a microwave, radar, TV satellite terrestrial or antenna system. Its purpose is to provide dry pressurised air to the aerial transmission tower, the waveguide itself and its associated components.

The air pressure supplied by the waveguide dehydrator is elevated above atmospheric, thus protecting against the ingress of moisture from changing weather conditions, and dried to the extent that this air does not condensate, therefore maintaining signal quality.

The pressure available at the outlet, which can number one to twenty (generally 3 – 10), can be set by a panel mounted regulator, which can be tamperproof if required. Alarms, set at appropriate levels relative to the required output pressure are displayed on the front panel, but can also be monitored remotely.

Front panel controls are kept to a minimum; those included are to give operator confidence without necessary intervention.

A small pressure vessel is incorporated within the waveguide dehydrator to ensure a stop-start cycle, rather than the integrated compressor running continually. A differential pressure switch controls compressor operation. This vessel stores dry air at increased pressure, being drawn off to the waveguide at the lower pressure set by the regulator. This also has the added benefit of providing extra capacity in the event of a sudden increase in dry air requirement, giving a bit of added time to carry out repairs.

A small bleed of air can be deliberately introduced to ensure a regular change of air within the waveguide system as felt necessary.

Drallim waveguide dehydrators all utilise a well proven heatless reactivation twin-bedded desiccant principle. Electronic timing and humidity detection system is inbuilt that prevents insufficiently dried air from being stored, and therefore entering the waveguide, in the event of any internal issues. This system is fail-safe.